There is a whole huge range of gears your K5 could have had from 3.08 all the way up to 4.56....The military M1009 would have had 4.56. With your 700r4 I would guess you would be between 3.08-3.42, you can easily check by looking in the glove compartment at the RPO code list, look for:
GQ1 -- AXLE REAR, STD RATIO
GT4 -- AXLE REAR, 3.73 RATIO
GT5 -- AXLE REAR, 4.10 RATIO
GU4 -- AXLE REAR, 3.08 RATIO
GU5 -- AXLE REAR, 3.23 RATIO
GU6 -- AXLE REAR, 3.42 RATIO
G80 -- AXLE REAR, LIMITED SLIP (POSITRACTION)
HC4 -- AXLE REAR, 4.56 RATIO
If you want to run 33s your best option would be to find a set of takeoff 10 bolts from a CUCV Blazer with 4.56, they usually aren't hard to find because many swap them for the D60/14 bolts from the CUCV trucks.